1. Field of the Invention
The present invention relates generally to a fuel delivery system for an engine, and more particularly, to a fuel injector mounting arrangement.
2. Description of the Related Art
Motorcycles are often equipped with engines employing a fuel-injection-type fuel delivery system to deliver fuel to a combustion chamber of the engine. Such a fuel delivery system, especially in high performance motorcycles, may include a fuel injector positioned adjacent an opening of an intake passage of the engine. The fuel injector is configured to deliver a fuel charge to the intake passage and may be used in combination with an additional fuel injector positioned downstream from the intake passage opening or, alternatively, positioned in direct communication with the combustion chamber. In such an arrangement, the fuel injector adjacent the intake passage opening is referred to as a “secondary” fuel injector, while the downstream fuel injector is referred to as the “primary” fuel injector. Typically, the primary fuel injector provides fuel to the combustion chamber during all running conditions of the engine and the secondary fuel injector provides supplemental fuel to the combustion chamber during selected running conditions, such as when the engine is experiencing a high load or a rapid increase in engine speed, for example.
In one prior arrangement, the secondary fuel injector is supported within an air cleaner box by a support frame. The support frame is a framework-type member that supports the secondary fuel injector from the end of an inlet duct, which defines the opening of the intake passage. That is, the support frame includes a first end connected to the inlet duct, a second end for supporting the fuel injector, and a body portion connecting together the first and second ends. The body portion of the support frame between the first and second ends is made up of a number of stays, or arms, interconnecting the first and second ends of the support frame. Specifically, in the prior arrangement, three stays are provided to interconnect the first and second ends of the support frame. Accordingly, the body portion of the support frame is partially open to permit air to enter the inlet duct and move toward the combustion chamber of the engine through the intake system, which includes a throttle body for controlling a volume of air permitted to enter the combustion chamber.
Although the inclusion of a secondary fuel injector provides a potential increase in engine performance, the support frame of the type described above has numerous disadvantages. Significantly, the stays, or arm members, that extend from the inlet duct and of the support frame to support the fuel injector interfere with a flow of air entering the intake passage through the inlet duct. Accordingly, the resistance to a flow of intake air into the engine is increased, which results in a reduction in the performance of the engine. Furthermore, the inlet duct, support frame, and secondary fuel injector must be disassembled in order to remove the air cleaner box and/or the throttle body, thus increasing the amount of time needed to perform certain routine maintenance procedures to the engine.
In addition, in order to accommodate the secondary fuel injector, support frame and associated components, such as a fuel rail, and also to provide a clearance space between the secondary fuel injector and the air cleaner box, the size of the air cleaner box is large. Typically, the air cleaner box is positioned below the fuel tank of the motorcycle. As a result, when the size of the air cleaner box is enlarged, the size of the fuel tank is often decreased in order to compensate, thereby reducing a mileage range of the motorcycle per tank of fuel. Furthermore, the support frame adds to the weight of the motorcycle and also increases the manufacturing cost.